The present invention relates to a structure for cooling a process cartridge of an image forming apparatus including a photoreceptor drum by which a toner image is transferred onto a recording medium, and a recovery box into which residual toner is recovered, wherein the recovery box is disposed above a fixing unit by which the toner image transferred onto the recording medium is thermally fixed.
In a conventional image forming apparatus, residual toner on a photoreceptor drum is recovered into a toner recovery box, and when the toner recovery box has been loaded fully with the recovered toner, or when a predetermined period of time has passed, the toner recovery box is replaced or the recovered toner in the recovery box is discharged.
In general, this toner recovery box is incorporated into a process cartridge together with the photoreceptor, and in many cases, the toner recovery box is disposed above a fixing unit.
However, when the toner recovery box is disposed in a position above a fixing unit, the toner contained in the recovery box is fused by the heat produced by the thermal fixing unit, and the fused toner is solidified when it is cooled. The solidified toner is formed into a lump in the vicinity of the inlet of the toner recovery box, which decreases the capacity of the toner recovery box, and in some cases, the toner recovery box is blocked by the lump.
In order to prevent such a problem, the following countermeasures have been taken:
(1) The toner recovery box is disposed at some distance away from the fixing unit which is a heat source.
(2) A fan is provided on one side of the image forming apparatus so that cooling air is introduced from the outside into the space defined by the toner recovery box and the fixing unit in order to cool the toner recovery section.
However, the problems with such an apparatus are that:
(1) A large space is required between the toner recovery box and the fixing unit, so that the size of the image forming apparatus becomes large.
(2) Flow velocity of introduced air is low, so that its cooling efficiency is low.
In a conventional image forming apparatus, handles are provided on both sides of the process cartridge so that the process cartridge can be easily attached to and detached from the apparatus.
A problem with such handles is that the size of the apparatus in the longitudinal direction is increased.
It is a primary object of the present invention to provide a structure for cooling a process cartridge of an image forming apparatus, characterized in that: the size of the space required in the apparatus, is reduced; the toner recovery box is effectively cooled; and the apparatus is made compact.